How do I view the details of a digital certificate .cer file?

OpenSSL will allow you to look at it if it is installed on your system, using the OpenSSL x509 tool.

openssl x509 -in cerfile.cer -noout -text

The format of the .CER file might require that you specify a different encoding format to be explicitly called out.

openssl x509 -inform pem -in cerfile.cer -noout -text

or

openssl x509 -inform der -in cerfile.cer -noout -text

On Windows systems you can right click the .cer file and select Open. That will then let you view most of the meta data.

On Windows you run Windows certificate manager program using certmgr.msc command in the run window. Then you can import your certificates and view details.

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